This application solicits support for the Nutrition Coding Center (NCC) at the University of Minnesota to act as the nutrition coordinating unit for the National Cancer Institute (NCI) cooperative agreement for a trial to test the effects of a low fat diet on survival in stage II breast cancer patients. The first year of the study will include a protocol development stage and a feasibility study involving approximately 150 patients at three clinical centers. Pending successful outcome of the feasibility study, a full scale trial involving approximately 2000 patients at 30 clinical centers will be launched in the second year of the study. The NCC proposes to work collaboratively with the study investigators and the NCI staff to develop a common dietary protocol for the multicentered trial. This includes development in three major areas: dietary data collection for research purposes; dietary intervention; and dietary data collection for counseling and adherence monitoring. A low fat food plan that can be individualized to meet food preferences of each patient, counseling strategies and supporting materials for achieving and maintaining the low fat (20% of total kilocalories) diet, and training procedures for both the research and the intervention dietitians are proposed. The diet history technique is recommended as the methodology for the research component of the trial, and frequent randomly spaced 24 hour recalls collected by telephone interview are proposed for compliance monitoring. The dietary data will be processed according to standardized procedures, and nutrients will be calculated for analysis and for compliance monitoring. Quality control procedures are proposed for each component of the dietary data collection. NCC investigators will collaborate with the other trial investigators and the NCI staff in the analysis and interpretation of the dietary data.